This application pertains to the art of servoactuators, and more particularly to a servoactuator for controlling the position of a ram which is connected to a controlled member. The ram may be connected to an air inlet ramp on a jet aircraft or to another controlled member.
In devices of the type described, failure of the normal controls due to battle damage or other emergency conditions makes it desirable that the controlled member have a dual mode operation; i.e., when failure occurs during mode A, the controlled member be returned at a controlled rate to a passive position; when failure occurs during mode B, the controlled members would be held in its existing position. In devices of the type described, the ram is often connected through a number of separate automatic valves which sense a failure in the control system to fix the ram in its existing position or retract it to a passive position.
Prior devices of this type include servovalves for controlling the position of the ram during normal operation, and additional servovalves and pressure operated valves for operating the ram in the event of a failure in the normal control system. The use of separate servovalves and pressure operated valves for accomplishing the dual mode functions during an emergency condition makes the servoactuator less reliable, heavier, more costly and complicated.